A 65-year-old white man presents with red lesions on his arms and legs. The lesions are asymptomatic and have increased in number over the past 2 years. He admits to ample sun exposure since early childhood and now regularly uses sunscreen. He has no prior history of skin cancer. On examination, multiple erythematous patches and thin plaques of varying sizes are found on his lower arms and legs.
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Disseminated superficial actinic porokeratosis (DSAP) is the most common form of porokeratosis. The age of onset for this disease may be as early as the third or fourth decade of life, and the condition is inherited as an autosomal-dominant trait with penetrance that increases with age. Patients typically report a history of extensive sun exposure.1
The distribution of DSAP is normally found on the extensor surfaces of the arms and legs. Lesions on the face are a less common finding, and the disease typically does not occur on the palms or soles. It presents as multiple, flat to barely elevated, brownish red patches on the extremities.2 The number of lesions can range from several to a few hundred.3
Although malignant transformation is exceedingly uncommon, many patients have concerns over the cosmetic appearance of DSAP. Successful treatment of multiple lesions is challenging. Clearance has been reported with topical 5-fluorouracil, retinoids, imiquimod, and cryosurgery.4
John Pappas is a medical student at the Geisinger Commonwealth School of Medicine in Scranton, Pennsylvania. Stephen Schleicher, MD, is an associate professor of medicine at the Commonwealth Medical College in Scranton, Pennsylvania, and an adjunct assistant professor of dermatology at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia. He practices dermatology in Hazleton, Pennsylvania.
- Sertznig P, von Felbert V, Megahed M. Porokeratosis: present concepts. J Eur Acad Dermatol Venereol. 2012;26:404-412.
- Shumack SP, Commens CA. Disseminated superficial actinic porokeratosis: a clinical study. J Am Acad Dermatol. 1989;20:1015-1022.
- Schwarz T, Seiser A, Gschnait F. Disseminated superficial “actinic” porokeratosis. J Am Acad Dermatol. 1984;11:724-730.
- Wolff K, Johnson RA, Saavedra AP. eds. Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology. 7th ed. New York, NY: McGraw-Hill; 2009.